As described in earlier posts on this blog, the Second World War marked a major turning point for the development of the modern plastics industry. Shortages of important materials and manufactured products, including glass, steel, and rubber, among others, led entrepreneurs in the United States to develop new materials that could be produced cheaply and in large volumes and stand up to the demands of the war.
Like so many technologies to come out of the war, CR-39, the resin from which many modern eyeglasses are made, took a circuitous path to its current application.
(many of the stories in this article can be explored in more detail by reading this booklet, produced by PPG industries)
Plastics, with their ability to be produced cheaply, their durability, and their low weight to strength ratio, were an obvious choice for materials scientists looking for new solutions. In 1940, scientists at the Columbia Southern Chemical Company, based in the town of Barberton, Ohio, were closing in on the formula for an exciting new plastic compound. The new compound had several useful attributes: it could be laminated with thin sheets of cloth, paper, or other materials to produce a strong, light compound – the first reinforced plastic.
Soon after its discovery CR-39, it was being used widely, primarily in the production of the B-17 bomber. The plastic was used to build lightweight fuel tanks, which were coated on the inside with a rubbery compound to prevent leaks if hit with shrapnel or bullets. It was also used to build fuel indicator lines – literally clear tubes in the cockpit through which fuel flowed on the way to the engines, which pilots could check to ensure fuel was flowing well.
After the war, all wartime government contracts were cancelled, leaving Columbia with a tanker rail car containing 38,000 lbs (~19,000 kg) of CR-39 resin.
Searching for a civilian market for the resin, the company found a buyer in Dr. Robert Graham, an applied optician recently out of school (Dr. Graham’s obituary provides a detailed biography). Despite government rules precluding civilian use during the war, Dr. Graham was able to obtain several gallons of CR-39 and experiment with it. He discovered that the compound could be used to produce lenses that were optically clear, light, and incredibly scratch-resistant. Dr. Graham jumped at the chance to buy Columbia’s extra tanker of resin.
In the next post of this two part series, we’ll look at the technical challenges Dr. Graham had to overcome before CR-39 was ready for use in commercial eyeglass lens production.